In this editorial, Joseph Farah suggests a radical notion: pass a test in order to qualify to vote. Of course, this idea has already been discussed at tuscanycircle in this thread. In the editorial, Farah provides a link to an online quiz comprised of some of the "more difficult" questions from the U.S. citizenship test. (I'd hate to see the easy ones.) He suggests that anyone who can't get 80% of these questions right shouldn't be allowed to vote.
Given that the questions cover just the basics of the history and structure of the American government, I'm inclined to agree with him. This quiz sets the bar rather low, in my opinion, and yet it's likely that the majority of voters today couldn't score 80%. I say, fine. Let 'em sit out a few elections until they get off their butts and learn something about the country they are trying to run.



Other criteria for voting
I've heard a few other criteria that should be used to determine eligibility to vote (in presidential elections anyway) and want to pass them on for discussion.
1) Only landowners should be able to vote, as in the old days. Determine the definition of "landowner": one that owns land outright with or without a bldg(s) on it; one that "owns" land via a mortgage; commercial owners of land & real estate.
2) Only men should vote. (Yes I've seen the threads here but reiterate.)
3) Only those who pay income taxes should vote. Determine exceptions to this rule, i.e. retirees who paid taxes all their lives but don't anymore.
4) Age requirement above 18 yrs. old, say, 21 or 25.
And last night, I heard that the age limit imposed on presidents is 35 yrs. old because back in the day when this limit was created, people only lived to be in their late 30s or 40s as a average. Today's average longevity is around 75. Taking that into account, and using our forefathers' standard, that should make our current age limit for presidents to be around 68. So you couldn't even run for president without quite a few more years under your belt, which makes quite a lot of sense to me.